Method and apparatus for obtaining sound



Jan. 22', 1963 J. P. KUCHERA 3,075,044

' unsmon AND APPARATUS FOR OBTAINING scum:

Filed May 5, 1958 MIXER TRANS- gs gg DUCER MODULATOR DETECTOR 3e 48 ./3O CARRER VARIABLE OSCILLATOR FREQUENCY c 20 OSCILLATOR 32a OUTPUT MEANS 34 AUDIO T0 DETECTOR 22 AUDIO 52b OSCILLATOR 0% MODULATOR 56 TO AUD|O OSCILLATORS 50c m Vlu CARRlER figs OSCILLATOR flu AUDIO OSCILLNggR INVENTOR.

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OSCILLATOR 28 JOSEPH P. KUCH ERA A TTOR/VE Y United States Patent 01 FQR UBTAHNENG This invention relates to the modification of characteristics of sounds and more particularly to methods and apparatus for accomplishing such modifications through the agency of frequency conversions.

In general, sounds may be modified by changing the pitch, tonal structure, harmonic relationship, or relative amplitudes of the frequency components of the sounds.

Such modifications are often desirable and sought after in the entertainment field, where unusual sounds are often required to supplement more conventional music or to create an aura of unreality in science fiction and psychological dramas. Furthermore, as the musical art progresses, composers are constantly seeking new means for expressing music. They are constantly trying to break through the restrictions imposed by more conventional musical instruments.

It is accordingly a general object of the invention to provide methods and apparatus for producing new and unusual sounds by modifying the characteristics of conventional sounds.

it is another general object of the invention to provide methods and apparatus for producing new and unusual sounds through the modification of the characteristics of conventional sounds by converting their component frequencies to dirTerent frequencies.

It is a more specific object of the invention to provide means in the field of recordings for creating unusual sounds from conventional sounds.

It is another more specific object of the invention to provide means for creating unusual sound effects for the dramatic arts.

It is a further object of the invention to provide an accessory for a conventional musical instrument which permits a performer to modify the sounds produced by the conventional musical instrument.

Briefly, in accordance with one aspect of the invention, a method is provided for changing the characteristics of a sound transduced to an electrical signal having a first band of frequencies in the audio spectrum of frequencies by converting the electrical signal to a second electrical signal. The second electrical signal has a second band of frequencies. The second electrical signal is further converted to a third electrical signal which has a third band of frequencies. In another embodiment of this aspect of the invention, the first is mixed with the third electrical signal.

In another aspect of the invention, apparatus is provided to accomplish the method of modifying the characteristics. In particular, apparatus is provided which includes a signal source for an electrical signal having a first band of frequencies in the audio spectrum of frequencies. Frequency converting means convert the electrical signal from the signal source to an electrical signal having a second band of frequencies. Means are further provided for converting the electrical signal having the second hand of frequencies to an electrical signal having a third band of frequencies. In another embodiment of this aspect of the invention, mixing means are included for mixing the first electrical signal with the third electrical signal.

Other objects, features and advantages of the invention will be evident from the following detailed description 3,0?5,0dd Patented Jan. 22, 1963 ice when read in connection with the accompanying drawings wherein:

FIG. 1 is a block diagram of the apparatus for changing the characteristics of sounds, in accordance with one aspect of the invention, and

FIG. 2 is a block diagram of a variable frequency signal source for incorporation with the apparatus of FIG. 1, in accordance with an alternate embodiment of the invention.

In FIG. 1 a sound from a sound source 10, for example, a human singing or playing a conventional musical instrument is converted to an electrical signal having a band of frequencies in the audio spectrum by a transducer 12 which may be a conventional microphone. The transducer 12. is coupled via line 14 to modulator 16 to modulate a carrier frequency signal received via a line 18 from a carrier oscillator 20.

Although new types of modulation are possible, single side band amplitude modulation will be assumed. In any type of amplitude modulation the amplitude of a constant frequency carrier-signal is varied in'accordance with the instantaneous amplitude of the modulating signal. In general, there is a heterodyning action which results in the generation of a signal having a component with a frequency equal to the carrier frequency, a component having a band of frequencies (the lower side band) equal to the difference between the carrier fre quency and the frequencies of the modulating signal, and a component having a band of frequencies (the up per side band) equal to the sum of the carrier frequency and the frequencies of the modulating signal. In a single side band system the carrier component and one of the side bands is suppressed or not transmitted. Single side band modulation may be accomplished by using the balanced modulator shown and described on page 551 of Radio Engineers Handbook, First Edition, by Frederick E. Terman, published by McGraw-Hill in 1943. Such a modulator will suppress the carrier component. By incorporating in the balanced modulator a band pass filter for passing only one of the side bands, a single side band is transmitted. Therefore, the electrical signal from the transducer 12 having a band of frequencies in the audio spectrum is converted by modulator 16 to a second electrical signal having a second band of frequencies usually in the radio frequency spectrum.

The detector 22, a conventional single side band detector, receives the electrical signal from the modulator 16 via the line 24. Coupled to the detector 22 via the line 26 is a variable frequency oscillator 28, which is controllable by an operator, such as, a recording engineer or musician. In general, a second heterodyning action takes place in the detector 22. Usually in single side band reception the frequency of the signal from the variable frequency oscillator 2 is adjusted to equal the suppressed carr-ier frequency. The resulting sum and difference frequencies generated by the detector 22 are filtered to permit only the passage of the difference frequency component. This difference frequency component is the original modulating signal, i.e., the signal transmitted from the transducer 12.

However, by adjusting the frequency of the variable frequency oscillator 28 to be different from the suppressed carrier frequency, and in particular, by an increment in the audio spectrum the difference frequency component is a transposition of the modulating signal. For example, if the signal from the transducer 12 has a band of frequencies from 1,000 cycles to 3,000 cycles and the carrier frequency is 500,000 cycles, upper side band transmission by modulator 16 yields a signal having a frequency band from 501,000 cycles to 503,000 cycles. When the signal generated by the variable frequency oscillator 28 is 500,000 cycles, the difference component transmitted from the detector 22 has a frequency band from 1,000 cycles to 3,000 cycles. The original signal, the electrical signal from transducer 12, is detected. If, however, the variable frequency oscillator is adjusted to generate a signal having a frequency of 498,000 cycles, the electrical signal transmitted from the detector 22 will have a difference component with a frequency band from 3,000 to 5,000 cycles. In effect, the original signal has been transposed upward 2,000 cycles in frequency. When the transposed signal is reconvented by a transducer to a sound, the resultant sound .will be higher in. pitch than the sound from the sound source By varying the frequency of the signal generated by the variable frequency oscillator 2-8 during the generation of a sound by the sound source 10 predetermined and planned transpositions in the pitch of the resultant sound can be obtained. In this manner unusual sounds and sound effects may be obtained from conventional sound sources.

In one embodiment of the invention the output signal from the detector 22 is fed via the line 30 and single-pole double-throw switch 32 to an output means 34. The output means 34 may be a conventional loudspeaker for immediate recreation of the sound or a tape recorder for reproduction at a later time.

In an alternate embodiment of the invention, the moving contact 32a is positioned against the fixed contact 32b of the single-pole, double-throw switch 3% connecting the output terminal or a conventional mixer =38 via line 48 to the output means 34. The electrical signal from the detector 2-2 is fed via a line 36 to one input terminal of the mixer 38. The second input terminal of the mixer 38 is connected via the line 40 to the output of transducer 12.

The electrical signal from the transducer 1 2 is mixed with the signal from the detector 22 to generate an electrical signal which when fed from the output terminal of the mixer 38 via the line 48 and single-pole double-throw switch 32 to the output means 34 produces a different sound.

It should be noted that the apparatus can work equally well with the carrier oscillator 20 and the variable frequency oscillator 28 interchanged. Although the variable frequency oscillator 28 may be a conventional oscillator with a variable capacitor in its tuned circuit for controllably varying the resonant frequency, FIG. 2 shows a variable frequency oscillator 28' suitable for control via a keyboard. A plurality of audio oscillators 50 are coupled respectively in parallel via finger operable switchcs 52 and junction 54 to a first input terminal of a modulator 56. The modulator 56 may be similar to the modulator 16 of FIG. 1. A carrier oscillator 60 is coupled via a line '58 to a second input terminal of the modulator 56. Carrier oscillator 60 may be similar to carrier oscillator 20 or carrier oscillator 20 can simultaneously feed the modulator 16 of FIG. 1 and the modulator 55.

In operation, each of the audio oscillators 50 generates a constant frequency signal. The frequencies generated by the audio oscillators 50 are separated from each other by predetermined amounts such as octaves. The carrier oscillator 60 may transmit a signal having a frequency equal to the carrier frequency of the signal transmitted by :the carrier oscillator 20. Thus, with none of the switches :52 closed the electrical signal transmitted from the detector 22 (-FIG. 1) is the same as the electrical signal trans- :mitted from the transducer 12. However, when one of the switches 52 is closed the signal transmitted from the modulator 56 has a frequency different from the carrier frequency and the detector 22 transmits thesignal from transducer 12 transposed by a number of cycles equal to the frequency of the audio oscillatorSO associated with the closed switch 52. Thus, by fingering the switches 52, :according to a predetermined routine, the characteristics -of the sound from the sound source 10 are modified when reproduced by theoutput means 34.

There has thus been shown methods and apparatus for producing new and unusual sounds by modifying the characteristics of conventional sounds through the agency of frequency conversions. There has been further shown means usable in the recording field for creating unusual sounds. The apparatus as disclosed is also useful as an accessory for a conventional musical instrument for permitting a performer to modify the sounds produced by the conventional instrument.

While only a limited number of embodiments of the invention have been shown and described in detail, it will now be obvious to those skilled in the many art modifications and variations "which accomplish many or all of the objects and realize advantages of the invention without departing from the spirit of the invention as hereinafter claimed.

1 claim:

1. Apparatus for changing the characteristics or" a first sound transduced to a first electrical signal having a first band of frequenciesin the audio spectrum of frequencies comprising a source of a constant frequency signal, a modulating means responsive to said, first electrical signal and said constant frequency signal source for transmitting a second electrical signal having a second band of frequencies, a source of a controllably variable frequency signal, means responsive to said modulating means and said controllably variable frequency signal source to transmit a third electrical signal having a third band of frequencies, said third band of frequencies being in the audio spectrum of frequencies and means for converting said third electrical signal to a second sound, the difference in frequency between the constant frequency signal and the controllably variable frequency signal being sufiicient to provide an audibly perceptive difference between said first and second sound.

2. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies in the audio spectrum of frequencies related to said first sound, a constant frequency oscillator for generating a signal of a constant frequency, a single side band suppressed carrier modulating means responsive to said transducer and said constant frequency oscillator, a controllable variable frequency signal source for generating a controllably variable frequency signal, detection means rmponsive to said single side band suppressed carrier modulating means and said controllably variable frequency signal source for transmitting a signal having a second band of frequencies, said second hand being in the audio spectrum of frequencies and means responsive to said detection means for generating a second sound, the difference in frequency between said constant frequency signal and the controllably variable frequency signal being sufficient to provide an audibly perceptive difference between said first and second sounds.

3. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies in the audio-spectrum of frequencies related to said first sound, a constant frequency oscillator for generating a signal of constant frequency, a single side band suppressed carrier modulating means responsive to said transducer and said constant frequency oscillator, a controllably variable frequency signal source for generating a controllably variable signal, said controllably variable frequency signal source including a second constant frequency oscillator, a plurality of audio-frequency oscillators and a single side band suppressed carrier modulator responsive to said constant frequency oscillator and selectively responsive to said audio-frequency oscillators, detection means responsive to said single side band suppressed carrier modulating means and said controllably variable frequency signal source for transmitting a signal having a second hand of. frequencies, said second band being in the audio spectrum of frequencies and means responsive to said detection means for generating a second sound, the difference in frequency between said constant frequency signal and the controllably variable frequency signal being sufficient to provide an audibly perceptive difference betewen said first and second sounds.

4. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies in the audio spectrum of frequencies related to said first sound, first means for converting the signal from said transducer to a signal having a second band of frequencies, means for converting the signal having the second band of frequencies to a signal having a third band of frequencies, mixing means responsive to said transducer and said second means for mixing the signal having the first band of frequencies With the signal having the third band of frequencies, and output means responsive to said mixing means for converting an electrical signal to a second sound.

5. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies in the audio spectrum of frequencies related to said first sound, a first signal source of a constant frequency signal, a modulating means responsive to said transducer and said first signal source for transmitting a signal in a second band of frequencies, a second signal source of a controllably variable frequency signal, means responsive to said modulating means and said second signal source for generating a signal having a third band of frequencies, mixing means responsive to said transducer and said modulating means for mixing the signal having the first band of frequencies with the signal having the third band of frequencies, and output means responsive to said mixing means for converting an electrical signal to a second sound.

6. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies, related to said sound source, in the audio spectrum of frequencies, a constant frequency oscillator for generating a. signal of a constant frequency, a single side band suppressed carrier modulating means espousive to said transducer and said constant frequency oscillator, a variable signal source for generating a controllably variable frequency signal, a detection means responsive to said single side band suppressed carrier modulating means and said variable signal source, a mixer responsive to said detection means and said transducer, and output means responsive to said mixer for converting electrical signals to a second sound.

7. Apparatus of claim 6 wherein said variable signal source includes a constant frequency oscillator, a plurality of audio frequency oscillators, and a single side band suppressed carrier modulator responsive to said constant frequency oscillator and selectively responsive to said audio frequency oscillators.

8. Apparatus for changing the characteristics of a sound transduced to a first electrical signal having a first band of frequencies in the audio spectrum of frequencies comprising first means for converting said first electrical signal to a second electrical signal having a second band of frequencies, a plurality of electrical signal oscillators each having a different frequency of oscillation and second means responsive to said first means and selectively responsive to said electrical signal oscillators for converting said second electrical signal to a third electrical signal having one of a plurality of bands of frequencies in the audio spectrum of frequencies.

9. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies in the audio spectrum of frequencies related to said first sound, first means for generating a controllably variable frequency signal, second means for generating a constant frequency signal, a modulating means responsive to said transducer and one of said means for transmitting a signal having a second hand of frequencies, demodulating means responsive to said modulating means and the other of said means for generating a signal having a third band of frequencies, and output means responsive to said demodulating means for converting electrical signals to a second sound.

10. Apparatus for changing the characteristics of a first sound generated by a sound source comprising a transducer for generating a signal having a first band of frequencies in the audio spectrum of frequencies related to said first sound, first means for generating a controllably variable frequency signal, second means for generating a constant frequency signal, a single side band sup pressed carrier modulating means responsive to said transducer and one of said means, a detection means responsive to said single side band suppressed carrier modulating means and the other of said means, and output means responsive to said detection means for converting electrical signals to a second sound.

11. Apparatus for changing the characteristics of a first sound generated by a sound source comprising: a transducer for generating a signal having a first band of frequencies in the audio-spectrum of frequencies related to said first sound; first means for generating a controllably variable frequency signal, said first means including a constant frequency oscillator and a plurality of audio-frequency oscillators selectively controllable to transmit signals; second means for generating a constant frequency; a single side band suppressed carrier modulating means responsive to said transducer and one of said means; a detection means responsive to said single side band suppressed carrier modulating means and the other of said means; and an output means responsive to said detection means for converting electrical signals to a second sound.

References Cited in the file of this patent UNITED STATES PATENTS 2,059,719 Wilson et a1 Nov. 3, 1936 2,157,178 Kellogg May 9, 1939 2,176,526 Friend Oct. 17, 1939 2,268,813 Foster Jan. 6, 1942 2,315,249 DeRosa Mar. 30, 1943 2,421,424 Krevzer June 3, 1947 2,698,379 Boelens et al Dec. 28, 1954 2,794,854 Boughtwood June 4, 1957 2,882,394 Mortley Apr. 14, 1959 

1. APPARATUS FOR CHANGING THE CHARACTERISTICS OF A FIRST SOUND TRANSDUCED TO A FIRST ELECTRICAL SIGNAL HAVING A FIRST BAND OF FREQUENCIES IN THE AUDIO SPECTRUM OF FREQUENCIES COMPRISING A SOURCE OF A CONSTANT FREQUENCY SIGNAL, A MODULATING MEANS RESPONSIVE TO SAID FIRST ELECTRICAL SIGNAL AND SAID CONSTANT FREQUENCY SIGNAL SOURCE FOR TRANSMITTING A SECOND ELECTRICAL SIGNAL HAVING A SECOND BAND OF FREQUENCIES, A SOURCE OF A CONTROLLABLY VARIABLE FREQUENCY SIGNAL, MEANS RESPONSIVE TO SAID MODULATING MEANS AND SAID CONTROLLABLY VARIABLE FREQUENCY SIGNAL SOURCE TO TRANSMIT A THIRD ELECTRICAL SIGNAL HAVING A THIRD BAND OF FREQUENCIES, SAID THIRD BAND OF FREQUENCIES BEING IN THE AUDIO SPECTRUM OF FREQUENCIES AND MEANS FOR CONVERTING SAID THIRD ELECTRICAL SIGNAL TO A SECOND SOUND, THE DIFFERENCE IN FREQUENCY BETWEEN THE CONSTANT FREQUENCY SIGNAL AND THE CONTROLLABLY VARIABLE FREQUENCY SIGNAL BEING SUFFICIENT TO PROVIDE AN AUDIBLY PERCEPTIVE DIFFERENCE BETWEEN SAID FIRST AND SECOND SOUND. 